Conventional UV curing of inkjet printed ink is done in a number of ways, such as with one or two high powered mercury arc lamps, that fully polymerize the ink in one or more exposures. High-powered UV LED lamps may also be employed to replace the mercury arc lamps to work in a similar fashion. These LED or Mercury lamps can be located close to or remote from the print area.
Another method of curing is to pin the printed ink with a low power UV lamp, either mercury arc or LED, close to the print area. Then, as a post process, the pinned ink is exposed to a high power UV source (mercury or LED) to fully cure the ink.
In some applications where the ink is laid down, then exposed to low powered pinning UV lamps first, and then exposed to high powered curing UV lamps, there are a number of circumstances where the transition between low and high power creates undesirable artifacts in the cured ink.
Inkjet printing is extremely precise, and dots are laid down accurately, to within less than one thousandth of an inch. Unfortunately, the UV light used to cure the ink cannot easily be controlled with such precision. Therefore, there will always be light spillage into areas of the print that are not desirable. This light spillage can cause a gloss differential in the print, if the ink is not substantially cured when the variable level of UV hits it.
It would be advantageous to provide a structure, system and/or process that provide sufficient pinning of light sensitive ink before final curing, while reducing or eliminating image artifacts. The development of such a system, structure, and/or process would provide a significant advance.
It would also be advantageous to provide a structure, system and/or process that provides sufficient pinning of light sensitive ink before final curing, which can be controllably altered for a wide variety of inks and printing conditions. The development of such a system, structure, and/or process would provide a further significant advance.